Electric heating unit



Fell 6, 1945" n... N. HAMPTON ETAL 2,369,045

ELECTRIC HEATING UNIT Original Filed Feb. 8, 1940 2 :o J4 n .LN HAMPTON/NVENTORSAH SHANGLE ATTORNEY Pa'tented @s md5 stars mais arcanesancorato esamina leon N. Hampton, New Yorin. N. il., .irnos Shangle,Roselle, N. il., assignors to Te er phone Laboratories, incorporated,Ylorii. N. Y., a corporation oi New Yori;

Original application February il, 1940, Serial No. M7398, now Patent No.2,274,408, elated Fehn rulary 2li, 1942. Divided and this .lannary ll,i942, Serial No. 4252?@ 2 Claims.

of a heat treated plastic material which has good lll electricinsulating and good heat conducting characteristics. This core is formedwith a plurality of means in the form of a cylindrical portion, ahelically double threaded groove formed longitudinally thereof, a secondcylindrical portion and a collar portion, with means in the form ofterminals embedded in the collar portion dispOSed contiguous to thesecond cylindrical -portion for connecting with the resistance wirewound in the screw thread in the core and with lead-in Wires formingpart of the heating unit.

Means' in the form ci a metallic sleeve closed at one end andconstructed of a non-scaling alloy such as nicke1-si1ver serves as ahousing for the resistance wire and the core with the annular spaceformed between the core and the sleeve lled with a plastic materialsimilar to that of the core, such material adhesively uniting the core,the resistance wire and the nickel-silver sleeve into an homogeneousunit structure which has a high heat conductivity and a high dielectriccharacteristic.

lMeans in the form or a ceramic plug fitted into the open end of thesleeve serves for protecting the terminals embedded in the corel and theconnecting ends of the resistance wire wound thereon while forming aclosure at this end of the sleeve, the plug being provided with meansfor receiving a collar inwardly pressed from the sleeve for securing theplug in position in the sleeve, while the anchoring of the terminals inthe core avoids the breaking of the resistance wire connected theretoupon a. pulling force applied to the lead-in wires connecting with theterminals.

Other novel features and advantages of the invention will appear fromthe following description and by the claims appended thereto referencebeing had to the accompanying drawing in which:

Fig. 1 ls an assembly view;

Fig. 2 is a longitudinal sectional view thereof;

Fig. 3 is a plain view oi' the core nais embedded therein i and thetermll Fig. di is a cross-sectional view oi the core taken on line t-liof Fig. 3;

Fig. 5 is a left-end view; and

Fig. 6 is a cross-sectional view taken on line 6-6 of Fig. 2.

The heating element of the invention as shown in the drawing, consistsof a core C best seen in Fig. 3, made as by molding and heat treatingplastic material containing substantially 50 to 56 per centferro-silicate, 4e to 50 perucent Zircon and phosphoric acid as abinder. The core C is formed as by molding with a cylindrical portion3i, a double threaded screw portion 3l, a second cylindrical portionSlYland a collar portion 32, Figs; 2, 3, Il, 5 and 6, into which 'wireterminals such as 33 and 3d are embedded. The cylindrical portion 3c isformed with a radially projecting lug 35 provided for anchoring themiddle length portion of |.a helically 'coiled resistor wire 36noninductively Wound in the double threaded screw portion 3l of thecore, the resistance wire being made of a material known as kanthal"which comprises iron 67 per cent, chromium 25 per cent, aluminum 5 percent, cobalt 3 per-cent.

The ends of the resistor wire 36 are passed through openings and intoslots SL in the terminals 33 and 34 for connection at the peripherythereof and with the ends of lead-in conductors such as 3l and 38 ttedinto the terminals, the lead-in conductors 3l and 33 being made of analloy of manganese and nickel and are secured to the terminals bypressing the :free ends of the latter over their respective conductorsto form indentations as shown in Fig. 2. A sleeve 4D, Figs. l. 2 and 6,of a non-scaling material well known in the trade as nickel-silver,described in Metals Handbook, 1939 edition, closed at one end, serves asa casing for housing the core and the resistor wire 36 coiled thereonwhile the annular space formed by the sleeve 40 and the core is filledwith a plastic material 39 of a composition consisting of substantially50 per cent ferro-silicate, 50 per cent Zircon and phosphoric acid as abinder. This plastic material as used for the core and for lling theconcentric space between the core and the metallic sleeve in the heatingunit thus constructed when heat treated has been found to possess verynearly the dielectric property of phenol plastic and the thermalconductivity and hardness of cast iron while capable of resisting greattemperature changes and adhering well with the preformed core thusforming a continuous heat path therebetween, the sleeve and theresistance wire, the notches nl, n2, n3 and n4 in the collar 32 beingprovided for pershown in Fig. 2 is provided with two diaxnetricaliy`parallelly disposed bores telescopically engaging the terminals Il andIl to which the conductors I1 and 3l and the ends of the resistance wirel.

` are connected. the bead Il being held securely therein by pressing aridge r from the sleeve into a circular groove rl, formed at theperiphery oi the bead.

Heating units constructed according to this invention have been found topossess s high degree o! emciency and long life in actual service.

What is claimed is:

l. In an electrical heating unit, a core or a molded heat-hardenedmaterial consisting of 50 per cent silicon, 50 per cent zircon andphosphoric acid as a binder, a resistance wire coiled thereon, ametallic sleeve of a copper-nickel-zinc alloy housing said core Aandsaid wire. and a heathardened material consisting of 50 per centsilicon, 50 per cent zircon and phosphoric acid as a binder filling theconcentric space between said core and said sleeve and adhesivelyuniting said core, said wire and said metallic sleeve.

s,seo,oss

2. An electric heating unit comprising a molded core made of aheat-hardened plastic material. said core comprising a cylindricalportion having a radial projection, a double helical screw threadportion, a second cylindrical portion and A a collar portion, a pair ofdiametrically` opposite terminals embedded in said collar portion inparaliel relation to each other and in parallel rela- 20 ductors, ametallic sleeve housing said core and said wire, and a heat-hardenedplastic material iilling the concentric space between said lcore andsaid sleeve and adhesively uniting the whole to form a continuous heatpath, the heat-hard- 25 ened material for said core and said fillingconsisting of 50 per cent silicon, 50 per cent zircon and phosphoricacid as a binder.

LEON N. HAMPTON. AMOS H. BHANGLE.

